From 7cfa4b0a43286b1da3afa4f5f99d52e65a8f30fc Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 23 Jul 2007 18:33:14 +0300 Subject: [PATCH] Revert "KVM: Avoid useless memory write when possible" This reverts commit a3c870bdce4d34332ebdba7eb9969592c4c6b243. While it does save useless updates, it (probably) defeats the fork detector, causing a massive performance loss. Signed-off-by: Avi Kivity --- drivers/kvm/kvm_main.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c index 46efbe70801..a8d8db8e3cc 100644 --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -1070,10 +1070,8 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, return 0; mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT); virt = kmap_atomic(page, KM_USER0); - if (memcmp(virt + offset_in_page(gpa), val, bytes)) { - kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes); - memcpy(virt + offset_in_page(gpa), val, bytes); - } + kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes); + memcpy(virt + offset_in_page(gpa), val, bytes); kunmap_atomic(virt, KM_USER0); return 1; } -- 2.20.1